STRIATAL IMPLANTS OF FETAL STRIATUM OR GELFOAM PROTECT AGAINST QUINOLINIC ACID LESIONS OF THE STRIATUM

Previous studies in our laboratory have shown that intrastriatal impla nts of fetal striatum significantly attenuate excitotoxic damage resul ting from a 240 nmol quinolinic acid (QA) challenge delivered 7 days l ater. In contrast, animals with intrastriatal implants of other tissue types (adipose tissue, peripheral nerve or adrenal medulla) demonstra te a more limited, but consistent trend in protection from QA excitoto xicity. The present study was designed to test the hypothesis that par tial striatal protection found in animals receiving peripheral tissue grafts is due to the transplantation procedure eliciting a host respon se which attenuates excitotoxicity. Adult female Long-Evans rats recei ved either cellular (fetal striatum) or acellular (gelfoam) implants f ollowed 1 week later by a unilateral injection of 240 nmol QA into the grafted striatum. Animals were tested for rotational asymmetries befo re grafting, post-implantation, and after lesioning. Compared to basel ine rotational behavior, rats which received implants did not show cha nges in ipsilateral turning after QA lesions. This protective effect w as not limited to rotational behavior since improvements in spontaneou s locomotor activity were evident. In addition, the adipsia and aphagi a often associated with striatal lesions were ameliorated in both grou ps of grafted animals. Morphometric analysis demonstrated that endogen ous dopaminergic, cholinergic and enkephalinergic systems in the two t ransplanted groups sustained less excitotoxic damage than in the QA le sioned, non-grafted animals. These results are consistent with the hyp othesis that a host generated response activated by the implantation p rocedure provides a protective effect against QA excitotoxicity.